[LV] Fix MinBWs in WidenIntrinsic case (llvm#137005)

There is a bug in the computation and handling of MinBWs in the case of
VPWidenIntrinsicRecipe: a crash is observed in
VPlanTransforms::truncateToMinimalBitwidths due to a mismatch between
the number of recipes processed and the number of entries in MinBWs. Fix
handling of calls in llvm::computeMinimumValueSizes, and handle
VPWidenIntrinsicRecipe in truncateToMinimalBitwidths, fixing the bug.

Fixes llvm#87407.

Author: artagnon

llvm/lib/Analysis/VectorUtils.cpp

@@ -827,6 +827,11 @@ llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB,
     if (isa<PHINode>(I))
       continue;
 
+    // Don't modify the types of operands of a call, as doing that would cause a
+    // signature mismatch.
+    if (isa<CallBase>(I))
+      continue;
+
     if (DBits[Leader] == ~0ULL)
       // All bits demanded, no point continuing.
       continue;
@@ -882,7 +887,9 @@ llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB,
 
       // If any of M's operands demand more bits than MinBW then M cannot be
       // performed safely in MinBW.
-      if (any_of(MI->operands(), [&DB, MinBW](Use &U) {
+      auto *Call = dyn_cast<CallBase>(MI);
+      auto Ops = Call ? Call->args() : MI->operands();
+      if (any_of(Ops, [&DB, MinBW](Use &U) {
             auto *CI = dyn_cast<ConstantInt>(U);
             // For constants shift amounts, check if the shift would result in
             // poison.

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1639,7 +1639,8 @@ void VPlanTransforms::truncateToMinimalBitwidths(
            vp_depth_first_deep(Plan.getVectorLoopRegion()))) {
     for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
       if (!isa<VPWidenRecipe, VPWidenCastRecipe, VPReplicateRecipe,
-               VPWidenSelectRecipe, VPWidenLoadRecipe>(&R))
+               VPWidenSelectRecipe, VPWidenLoadRecipe, VPWidenIntrinsicRecipe>(
+              &R))
         continue;
 
       VPValue *ResultVPV = R.getVPSingleValue();
@@ -1712,7 +1713,7 @@ void VPlanTransforms::truncateToMinimalBitwidths(
       }
 
       assert(!isa<VPWidenStoreRecipe>(&R) && "stores cannot be narrowed");
-      if (isa<VPWidenLoadRecipe>(&R))
+      if (isa<VPWidenLoadRecipe, VPWidenIntrinsicRecipe>(&R))
         continue;
 
       // Shrink operands by introducing truncates as needed.

llvm/test/Transforms/LoopVectorize/pr87407-trunc-with-intrinsic.ll

@@ -0,0 +1,70 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 5
+; RUN: opt -passes=loop-vectorize -force-vector-width=4 -S %s | FileCheck %s
+
+define i8 @pr87407(i8 %x, i64 %y, i64 %n) {
+; CHECK-LABEL: define i8 @pr87407(
+; CHECK-SAME: i8 [[X:%.*]], i64 [[Y:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[ZEXT_X:%.*]] = zext i8 [[X]] to i64
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 4
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[Y]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <4 x i64> poison, i64 [[ZEXT_X]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT1]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP0:%.*]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> [[BROADCAST_SPLAT2]], <4 x i64> [[BROADCAST_SPLAT]])
+; CHECK-NEXT:    [[TMP1:%.*]] = trunc <4 x i64> [[TMP0]] to <4 x i1>
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ne <4 x i1> [[TMP1]], zeroinitializer
+; CHECK-NEXT:    [[TMP3:%.*]] = zext <4 x i1> [[TMP2]] to <4 x i32>
+; CHECK-NEXT:    [[TMP4:%.*]] = shl <4 x i32> [[TMP3]], splat (i32 8)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc <4 x i32> [[TMP4]] to <4 x i8>
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP6]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[TMP7:%.*]] = extractelement <4 x i8> [[TMP5]], i32 3
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], %[[LOOP]] ], [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ]
+; CHECK-NEXT:    [[MAX:%.*]] = tail call i64 @llvm.umax.i64(i64 [[ZEXT_X]], i64 [[Y]])
+; CHECK-NEXT:    [[CMP_MAX_0:%.*]] = icmp ne i64 [[MAX]], 0
+; CHECK-NEXT:    [[ZEXT_CMP:%.*]] = zext i1 [[CMP_MAX_0]] to i64
+; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i64 [[ZEXT_CMP]] to i32
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[TRUNC]], 8
+; CHECK-NEXT:    [[RES:%.*]] = trunc i32 [[SHL]] to i8
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT:    [[EXIT_COND:%.*]] = icmp ne i64 [[IV_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[EXIT_COND]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], %[[LOOP]] ], [ [[TMP7]], %[[MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    ret i8 [[RES_LCSSA]]
+;
+entry:
+  %zext.x = zext i8 %x to i64
+  br label %loop
+
+loop:
+  %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
+  %max = tail call i64 @llvm.umax.i64(i64 %zext.x, i64 %y)
+  %cmp.max.0 = icmp ne i64 %max, 0
+  %zext.cmp = zext i1 %cmp.max.0 to i64
+  %trunc = trunc i64 %zext.cmp to i32
+  %shl = shl i32 %trunc, 8
+  %res = trunc i32 %shl to i8
+  %iv.next = add i64 %iv, 1
+  %exit.cond = icmp ne i64 %iv.next, %n
+  br i1 %exit.cond, label %loop, label %exit
+
+exit:
+  ret i8 %res
+}